EPLIN as a Molecular Target of Genistein In Preventing Prostate Cancer Metastasis Genistein, a major dietary isoflavone whose consumption is associated with decreased rate of metastasis and reduced risk of mortality in patients, has emerged as a promising inhibitor of PCa metastasis. Nonetheless, the mechanism of action of genistein in blocking metastatic cascade in cancer cells remains largely unknown. In this application, we will test the hypothesis that the induction of EPLIN is a major mechanism wherein genistein inhibits the acquisition of invasiveness by PCa cells and prevents tumor metastasis. We proposed two Specific Aims. In Aim 1, we will elucidate the molecular mechanism by which genistein upregulates EPLIN and inhibits EMT in PCa cells. The hypothesis is that genistein induces EPLIN expression at transcriptional level, thereby inhibiting EMT and suppressing invasive phenotypes in PCa cells. We will determine whether genistein activates EPLIN promoter by inhibiting Snail-dependent repression of EPLIN promoter. The in vitro effects of genistein on EMT and invasiveness of PCa cells will be examined. This Aim will elucidate a novel mechanism of action of genistein in blocking the metastatic cascade in PCa cells. In Aim 2, we will determine the in vivo effects of genistein in upregulating EPLIN and preventing metastasis in pre-clinical PCa models. The hypothesis is that in vivo administration of genistein could effectively increase EPLIN expression and significantly reduce metastatic incidence in animal models. Two experimental models for PCa metastasis, i.e., TRAMP mice and orthotopic inoculation of PCa cells in SCID mice, will be used to evaluate the in vivo efficacy of genistein in upregulating EPLIN, inhibiting EMT and reducing metastatic incidence. These studies will validate EPLIN as a major molecular target of genistein, which could be exploited clinically for preventing PCa metastasis.